activating the modern return plant presented by michael e. mccracken eastern show ‘96 presented by...

Activating The Modern Return Plant

Presented By

Michael E. McCracken

Eastern Show ‘96

Presented By

Michael E. McCracken

Eastern Show ‘96

2 GTS Enterprises, Inc.Wednesday, September 18, 1996

Activating the Modern Return PlantTopics


Activating the Modern Return PlantReturn Path Overview

AM Fiber LinkCoaxial Distribution HeadendTransport

Drop


Activating the Modern Return PlantThe Forward & Return RF Spectrum

5MHz 750MHz

Return Forward

40MHz 54MHz

SystemSplit

2 3 4 5 6 …..


Activating the Modern Return PlantTwo-Way Amplifier

54-750MHz

5 - 40MHz 5 - 40MHz

54-750MHz

Forward Amplifier

ReturnAmplifier

Dip

lex

Filt

er

Dip

lex

Filt

er

C

H

L

H

C

L

From/ToHeadend

To/FromSubscriber


Activating the Modern Return PlantDiplex Filter Crossover

5MHz 750MHz

Return Forward

40MHz 54MHz

Crossover

Am

pli

tud

e


Activating the Modern Return PlantAM Fiber Link

Diplex Filter

Forward Receiver Forward Transmitter

Return ReceiverReturn Transmitter

Forward Fiber

Return Fiber

AM Optical Node

Hub or Headend

To/FromDistributionSystem


Activating the Modern Return PlantRF Impulse-Pay-Per-View

AM Fiber LinkCoaxial DistributionDrop

SettopTerminal

HeadendTransport

ControlSystem


Activating the Modern Return PlantRF-IPPV Frequency Allocation

5 MHz 40 MHz10 MHz 15 MHz 20 MHz 25 MHz 30 MHz 35 MHz

vv

15.45MHz 17.75MHz


Activating the Modern Return PlantRF-IPPV Bandwidth Utilization

15.45 MHz 17.75 MHz

2.3MHz23 Channel Slots

100kHz


Activating the Modern Return PlantHigh-Speed Cable Modems

AM Fiber LinkCoaxial DistributionDrop

SettopTerminal

HeadendTransport

Interface


Activating the Modern Return PlantCable Modem Frequency Allocation



Activating the Modern Return PlantCable Modem Bandwidth Utilization


1 MHz


Activating the Modern Return PlantCable Telephony

TelephoneInterface

AM Fiber LinkCoaxial DistributionDrop HeadendTransport

Interface


Activating the Modern Return PlantCable Telephony Frequency Allocation


50 kHz

1 Voice Channel = 50kHz


Activating the Modern Return PlantCable Telephony Bandwidth Utilization


240 Channels in 12MHz


Activating the Modern Return PlantStatus Monitoring

MonitoringSystem



Activating the Modern Return PlantStatus Monitoring Frequency Allocation


29.8MHz Typical


Activating the Modern Return PlantStatus Monitoring Bandwidth Utilization

5 MHz 40 MHz29.8MHz

250 kHz


Activating the Modern Return PlantInteractive Services

Video Server


DigitalSettop Terminal


Activating the Modern Return PlantInteractive Services Frequency Allocation

• One or more channels

• Frequency Agile


Signaling Channel


Activating the Modern Return PlantInteractive Services Bandwidth Utilization


1.0 MHz


Activating the Modern Return PlantCurrent Bandwidth Utilization


RF-IPPV Telephony

Cable Modem Status Monitoring

Interactive Services


Activating the Modern Return PlantProposed Bandwidth Allocation


RF-IPPV Telephony

Cable ModemStatus Monitoring Interactive Services


Activating the Modern Return PlantBandwidth Limitations

5MHz 750MHz

Return Forward

40MHz 54MHz


Activating the Modern Return PlantSegmented Reverse

FiberCable

Coaxial Distribution

Diplex Filter

Reverse Fiber Tx

Fiber Rx


Activating the Modern Return PlantBlock Conversion

OpticalReceiver

OpticalTransmitter

BlockConverter

BlockConverterCombiner

54 MHz 750 MHz

Reverse Block5 - 40MHz

Reverse Block5 - 40MHz

Upstream Blocks5 - 40 MHz

40 - 75 MHz75 - 110 MHz

110 - 145 MHz

35 MHz 35 MHz

54075


Activating the Modern Return PlantHigh-End Return

735 MHz

Forward

50 MHz 1 GHz

Return

900 MHz


Activating the Modern Return PlantThermal Noise

Carrier-to-Noise Ratio

Noise Energy

RF Carrier


Activating the Modern Return PlantNoise Accumulation: Forward

1 2

4 5

3


Activating the Modern Return PlantNoise Accumulation: Return

1 2 3

4 5


Activating the Modern Return PlantManaging Thermal Noise

Return TransmittersReturn Combining Network

Noise


Activating the Modern Return PlantRF Ingress

HA

M

HA

M

HA

M

HA

M

HA

M

40 M

20 M

15 M

CB

Lan

dM

ob

ile

40MHz

Land MobileCivil Air Patrol Civil Air Patrol

5.0MHz

Sub-Split Return Spectrum

Potential Ingress Sources


Activating the Modern Return PlantNon-RF Ingress

Power line conductedemissions and noise

Household electricmotor noise

Industrial electricmotor noise

Electrical switches

Electrostatic discharge


Activating the Modern Return PlantIngress Causes

DropDrop

Reports of 70 to 90% caused by drops and house wiring.

10 to 30% caused by coaxial plant problems.


Activating the Modern Return PlantDrop Cable

Tra

nsfe

r Im

peda

nce

Frequency

0MHz 1GHz

0 m/m

100 m/m

Headend Quad

60/40 Quad

60% Braid

Worse

Better

50MHz


Activating the Modern Return PlantRF Egress

Potential for Harmful Interference

HA

M

HA

M

HA

M

HA

M

HA

M

40 M

20 M

15 M

CB

Lan

dM

ob

ile

40MHz

Land MobileCivil Air Patrol Civil Air Patrol

5.0MHz

Sub-Split Return Spectrum


Activating the Modern Return PlantRules on Interference

• Concerned with “harmful interference”

– Radio navigation

– Safety of life and protection of property

– Radiocommunication services

• System Operator must eliminate the problem “immediately”

– Measures include service or even system shutdown


Activating the Modern Return PlantSummary

• Bandwidth is limited and must be carefully managed

• Thermal Noise is a natural phenomenon and must be managed

• Ingress points must be located and eliminated on a continuous basis

• Egress must be tracked down and eliminated to prevent interference with radio communications

• Bandwidth is limited and must be carefully managed

• Thermal Noise is a natural phenomenon and must be managed

• Ingress points must be located and eliminated on a continuous basis

• Egress must be tracked down and eliminated to prevent interference with radio communications


Activating the Modern Return PlantBasic Network

Headend•End of line•Far from Headend•Large house•Two outlets

•First tap•Closer to headend•Short drop•Small house•Three outlets


Activating the Modern Return PlantHeadend

Pad

Modulator

Combiner

Same Amplitude

RF Carriers

To Distribution


Activating the Modern Return PlantForward AM Fiber Links

Forward Tx Forward Rx

From Headend To Distribution

Fiber

Signal Input Signal Output


Activating the Modern Return PlantForward Unity Transmission

-24 -24 -24

+24 +24 +24 +24

ConditionEstablished

ConditionRepeated

FromHeadend

Gain = Loss

Output Level

Input Level

1 2 3 4

+24-24

0

+24-24

0


Activating the Modern Return PlantBasic Forward Amplifier

EQEQ InterstageSection

-20dBTest

-20dBTest

InputTest Point

OutputTest Point

PADInputAmp

OutputAmp


Activating the Modern Return PlantAmplifier Spacing

-24

+24 +24

1 2

-19

+24 +24

1 2

Obstacle(Water)

Normal Spacing

Short Spacing


Activating the Modern Return PlantAmplifier Pad

InputTest Point

InputAmp

+24dB

Desired Input = 11dBmVInput = 16dBmV

5

Attenuation24dB - 19dB = 5dB

Amplifier Output11dBmV + 24dB = 35dBmV

-19dB

Amplifier Input16dBmV - 5dB = 11dBmV


Activating the Modern Return PlantAmplifier Pad Application

-24 -20

+24 +24

+24

+24FromHeadend

1 2 3 4-22

5

-12

-11Pad: 24 - 24 = 0Input: 35 - 24 = 11

•Forward Pad used to achieve same input level on all amplifiers•Forward Pad used to achieve same input level on all amplifiers

+24

11dBmV

35dBmV

Pad: 24 - 12 - 11 = 1Input: 35 - 12 - 11 - 1 = 11

Pad: 24 - 20 = 4Input: 35 - 20 - 4 = 11

Pad: 24 - 22 = 2Input: 35 - 22 - 2 = 11


Activating the Modern Return PlantForward Amplifier Equalizer


-20dBTest

-20dBTest

InputTest Point

OutputTest Point

PADInputAmp

OutputAmp


Activating the Modern Return PlantCable Attenuation vs. Frequency

5 20 80 320 1280

1 2 4 8 16

4 x Frequency = 2 x Attenuation4 x Frequency = 2 x Attenuation

Attenuation Factor

Frequency in MHz


Activating the Modern Return PlantCable Loss Ratio

50 800 50 800

Flat Test Signal

Cable = 24dB at 800MHz6dB

24dB

50

8000 25

0 25 24 6

MHz

MHz

x dB dB

.

.

and


Activating the Modern Return PlantEqualizer Attenuation Curve

50 100 200 400 800

Att

enu

atio

n

Frequency in MHz

Equalizer

Cable

Equalizer + Cable


Activating the Modern Return PlantEqualizer Function

6dB

50MHz 100MHz 200MHz 400MHz 800MHz

8.5dB

16.5dB

13dB

12dB

17dB

8dB

19dB

1dB

Eq

ual

ize

r A

tte

nu

atio

n

24dB

25dB

Cable Attenuation

25dB 25dB 25dB



50 800

25dB

50 800

6dB24dB 25dB

Equalizer24dB

800MHz

Equalizer Input Equalizer Output

Equalizer Reference Frequency


Activating the Modern Return PlantPad and Equalizer Practice

-24 -20

+24 +24

+24

+24FromHeadend

1 2 3 4-22

5

-12

-11

Pad: EQ : Input:

+24

11dBmV

35dBmV

Pad: EQ : Input:

Pad: EQ : Input:

Pad: EQ : Input:

Pad: EQ : Input:

Includes EQ Loss


Activating the Modern Return PlantTransition to Tapped Feeder

-24 -20

+24 +24FromHeadend

1 2 3 4-17

+24

11dBmV

35dBmV

+30

35 - 17 = 18dBmV

18 + 30 = 48dBmV


Activating the Modern Return PlantEqual Loss Signal Splitting

-4 -4 -4 -4 -4 -4

-2 -2 -2 -2 -2

48dBmV

-4 -4 -4 -4 -4 -4

Distribution System with equal loss taps

44dBmV 38dBmV 32dBmV 26dBmV 20dBmV 14dBmV

•Unacceptable amplitude differences•Inefficient signal distribution


Activating the Modern Return PlantEqual Loss Distribution

-2 -2 -2 -2 -2

48dBmV

-1 -1 -1 -1 -1 -1

Distribution System with selectable attenuation


•Equal amplitude at all subscriber connections•Equal attenuation to all subscriber connections•Feeder amplitude preserved for additional distribution

32 29 26 23 20 17

Attenuation: (5 x 1) + (5 x 2) + 17 = 32dB

Amplitude: 48dBmV - 32dB = 16dBmv



• All signals aligned to common amplitude at Headend

• The Forward Fiber Link provides “transparent” transport

• The Coaxial Trunk system provides “Unity Transmission”

• The Coaxial Feeder provides equal distribution of available signal

• All signals aligned to common amplitude at Headend

• The Forward Fiber Link provides “transparent” transport

• The Coaxial Trunk system provides “Unity Transmission”

• The Coaxial Feeder provides equal distribution of available signal


Activating the Modern Return PlantBasic Return Network

Headend•End of line•Far from Headend•Large house•Two outlets

•First tap•Closer to headend•Short drop•Small house•Three outlets

Sources


Activating the Modern Return PlantSignal Combining

Pad

Modulator

Combiner

Same Amplitude

RF Carriers

To Distribution


Activating the Modern Return PlantReturn Path as a Combiner

SourceSource SourceSource SourceSource SourceSource

SourceSource SourceSource SourceSource SourceSource

CommonTest Point

Combiner

Settops

Objective: Achieve desired amplitude and quality at common test point.

Objective: Achieve desired amplitude and quality at common test point.

HFC Network


Activating the Modern Return PlantSignal Combining at the Home

TV 1

TV 2

-5.5dB

75’ @ 1.67 = -1.25dB35’ @ 1.67 = -.58dB

10’ @ 1.67 = -.17dB

+55dBmV

+55dBmV

1 2 3

49.3 48.948.3

+55dBmV

Cable Modem


Activating the Modern Return PlantTerminal Calibration

TV 1

TV 2

-5.5dB

75’ @ 1.67 = -1.25dB35’ @ 1.67 = -.58dB

10’ @ 1.67 = -.17dB

+54dBmV

+54.4dBmV

1 2 3

48.348.348.3

+55dBmV

Cable Modem


Activating the Modern Return PlantCombining in the Feeder Plant

-.5 -.5 -.5 -.5 -.5-1 -1 -1 -1 -1 -1


32 29 26 23 20 17

Attenuation: (5 x 1) + (5 x .5) + 17 = 24.5dBAttenuation: 32dB

Reverse Amplifier Input

1: 16.0dBmV 4: 20.5dBmV

2: 17.5dBmV 5: 22.0dBmV

3: 19.0dBmV 6: 23.5dBmV


1: 16.0dBmV 4: 20.5dBmV

2: 17.5dBmV 5: 22.0dBmV

3: 19.0dBmV 6: 23.5dBmV

1 2 3 4 5 6

1 2 3 4 5 6


Activating the Modern Return PlantTraditional Concept

-.5 -.5 -.5 -.5 -.5-1 -1 -1 -1 -1 -1

48dBmV 46.5dBmV 45dBmV 43.5dBmV 42dBmV 40.5dBmV

32 29 26 23 20 17

Attenuation: (5 x 1) + (5 x .5) + 17 = 24.5dBAttenuation: 32dB

Reverse Amplifier Input = 16dBmVReverse Amplifier Input = 16dBmV

1 2 3 4 5 6

654321 Terminal output adjusted to compensate for path conditions


Activating the Modern Return PlantUnity Loss in Return Path

-.5 -.5 -.5 -.5 -.5-1 -1 -1 -1 -1 -1

48dBmV

48dBmV

48dBmV

48dBmV

48dBmV

48dBmV

32 29 26 23 20 17


Uniform at 16.0dBmV


Uniform at 16.0dBmV

Maximum output level for best carrier/interference

ratio

Maximum output level for best carrier/interference

ratio

0 -1.5 -3 -4.5 -6 -7.5

1 2 3 4 5 6

Return Path Pad

Attenuation: 32dB Attenuation: (5 x 1) + (5 x .5) + 17 + 7.5 = 32dB


Activating the Modern Return PlantSplitters and DCs in the Return Path

-.5 -.5-8

-.5 -.5-1 -1 -1 -1 -1 -1

48dBmV

48dBmV

48dBmV

48dBmV

48dBmV

48dBmV

32 29 26 23 20 17

0 -1.5 -3 -4.5 -6 -7.5

1 2 3 4 5 6

-.5 -.5-1 -1

48dBmV

48dBmV

48dBmV

14 11 8

-5.5 -7 -8.5

7 8 9

-.5

-.5

Total Attenuation always = 32dB

Amplifier Input Always = 16dBmV

1 Values are arbitrary examples

Total Attenuation always = 32dB

Amplifier Input Always = 16dBmV

1 Values are arbitrary examples


Activating the Modern Return PlantBasic Reverse Amplifier


-20dBTest

-20dBTest

InputTest Point

OutputTest Point

PADInputAmp

OutputAmp

RvrsAmp

Dip

lexe

r

Dip

lexe

r

-20dBTest

-20dBTest

EQEQPAD

-20dBRev Inj


Activating the Modern Return PlantReverse Pads and EQs


-20dBTest

-20dBTest

InputTest Point

OutputTest Point

PADInputAmp

OutputAmp

RvrsAmp

Dip

lexe

r

Dip

lexe

r

-20dBTest

-20dBTest

EQEQPAD

-20dBRev Inj


Activating the Modern Return PlantReverse Pad Application

-5

-8

+10 +10ToHeadend

+10 +10-4

-2 +10

-5 -1

AB

Gain vs Attenuation

Path A = 10 - (4 + 1) = 5dB

Path B = 10 - (2 + 8) = 0dB

Gain vs Attenuation

Path A = 10 - (4 + 1) = 5dB

Path B = 10 - (2 + 8) = 0dB

Amplifier #3 Input

1 2 3 A

B


Activating the Modern Return PlantReverse Pad Application (con’t)

-5

-8

+10 +10ToHeadend

+10 +10-4

-2 +10

-5 -1

A B

Attenuation vs Gain

Path A = 10 - (4 + 1 + 5) = 0dBmV

Path B = 10 - (2 + 8 + 0) = 0dBmV

Attenuation vs Gain

Path A = 10 - (4 + 1 + 5) = 0dBmV

Path B = 10 - (2 + 8 + 0) = 0dBmV

Amplifier #3 Input

0dB Pad

5dB Pad

1 2 3 A

B


Activating the Modern Return PlantReverse Pad Exercise

EQEQPAD+10dB+10dB EQEQPAD+10dB+10dB

EQEQPAD+10dB+10dB

Reverse Amp A

Reverse Amp B Reverse Amp C

-4dB

-1dB

-8dB

-1dB


Activating the Modern Return PlantReverse Unity Transmission

-6 -6 -6

+6 +6 +6 +6

ConditionEstablished

ConditionRepeated

ToHeadend

Gain = Loss

Output Level

Input Level

+6-60

+6-60

1 2 3 4


Activating the Modern Return PlantReverse Equalizers


-20dBTest

-20dBTest

InputTest Point

OutputTest Point

PADInputAmp

OutputAmp

RvrsAmp

Dip

lexe

r

Dip

lexe

r

-20dBTest

-20dBTest

EQEQPAD

-20dBRev Inj


Activating the Modern Return PlantCable Attenuation vs. Frequency

5 20 80 320 1280

1 2 4 8 16

4 x Frequency = 2 x Attenuation4 x Frequency = 2 x Attenuation

Attenuation Factor

Frequency in MHz


Activating the Modern Return PlantCable Loss Ratio

50 800 50 800

Flat Test Signal

Cable = 24dB at 800MHz6dB

24dB

50

8000 25

0 25 24 6

MHz

MHz

x dB dB

.

.

and


Activating the Modern Return PlantEqualizer Attenuation Curve

5 10 15 20 40

Att

enu

atio

n

Frequency in MHz

Equalizer

Cable

Equalizer + Cable


Activating the Modern Return PlantReverse Equalizer Function

2.1dB

5MHz 10MHz 20MHz 40MHz

3dB

4dB

4.3dB

2.7dB

4.9dB

1dB

Eq

ual

ize

r A

tte

nu

atio

n

6dB

Cable Attenuation

7dB 7dB 7dB



5 40

7dB

5 40

2dB6dB 7dB

Equalizer6.0dB40MHz

Equalizer Input Equalizer Output

Equalizer Reference Frequency


Activating the Modern Return PlantReverse Pad and EQ Practice

-6 -5

+10 +10

+10

+10ToHeadend

-5

-8

-2

Pad: EQ : Atten:

+10

Pad: EQ : Atten:

Pad: EQ : Atten:

Pad: EQ : Atten:

Pad: EQ : Atten:

Includes EQ Loss

-1


Activating the Modern Return PlantReverse AM Fiber Links

Reverse Rx Reverse Tx

To Headend From Distribution

Fiber

Signal Output Signal Input



• All paths must have equal attenuation

• Reverse signals must be maintained at the highest possible levels

• 40MHz signals experience only about one fourth the cable attenuation of 750MHz signals

• Passive devices attenuate forward and reverse signals approximately the same

• All paths must have equal attenuation

• Reverse signals must be maintained at the highest possible levels

• 40MHz signals experience only about one fourth the cable attenuation of 750MHz signals

• Passive devices attenuate forward and reverse signals approximately the same


Activating the Modern Return PlantEarly Return Path Application

2 T9

Video/Audio returned to headend on Return Path channel

Return Path Channel translated to Forward Path channel

Subscribers view local video on Forward Path channel


Activating the Modern Return PlantBasic Alignment Technique

SignalSource

Technician 1

Injects calibrated test signal

Selects Pads and EQs

Technician 2

Informs Tech 1 of results


Activating the Modern Return PlantImproved Alignment Technique

2

Return Path signal displayed on analyzer

Technician views analyzer display on TV and makes adjustments to Return Path

SpectrumAnalyzer

Baseband Video

Camera views analyzer display

Camera output modulated to Forward Path channel

SignalSource


Activating the Modern Return PlantSweeping vs Balancing

Balancing with two carriers

• Only two reference points visible

Broadband Sweeping

• Hundreds of reference points


Activating the Modern Return PlantReverse Sweep Equipment

Headend UnitField Unit


Activating the Modern Return PlantTypical Sweep Display

5MHz 40MHz

5db/Div

Ref Lvl +20dBmV


Activating the Modern Return PlantReturn Path Activation Steps

• Install sweep system headend unit

• Configure sweep equipment

• Install and Align Reverse Fiber Link

• Install and Align reverse amplifiers in sequence, from first to last

• Install sweep system headend unit

• Configure sweep equipment

• Install and Align Reverse Fiber Link

• Install and Align reverse amplifiers in sequence, from first to last


Activating the Modern Return PlantInstalling the 3ST Transmitter

Co

mb

inin

g N

etw

ork

ForwardLaser

ForwardLaser

Return PathReceiver

Return PathReceiver

Ret

urn

Sig

nal

Bre

ak-o

ut

Diplex FilterH / L

Fiber Out

Fiber In

out

in

Sweep Signal -10 to -12dB

Telemetry Signal -5dB

Input -10dBmV to +10dBmv


Activating the Modern Return PlantConfiguring the 3ST Transmitter

• Enable Reverse Sweep

• Select Reverse Telemetry Carrier Frequency

• Create a Reverse Sweep Plan

• Select a Reverse Sweep Plan

• Enable Reverse Sweep

• Select Reverse Telemetry Carrier Frequency

• Create a Reverse Sweep Plan

• Select a Reverse Sweep Plan


Activating the Modern Return PlantSweeping a Fiber Node

ForwardReceiver

ForwardReceiver

ReverseTransmitter

ReverseTransmitter

LH

Fiber In

Fiber Out

From System

in out

3SR

External RF In

Forward Test Point

Fiber node


Activating the Modern Return PlantReverse Fiber Receivers

Return PathReceiver

Return PathReceiver

Ret

urn

Sig

nal

Bre

ak-o

ut

Diplex FilterH / L

Fiber In

in

Return PathReceiver

Return PathReceiver

Fiber In

Return PathReceiver

Return PathReceiver

Fiber In

Return PathReceiver

Return PathReceiver

Fiber In

Ret

urn

Sig

nal

Co

mb

iner

-8dB-11dB-0.5

-0.5

-0.5

+24dBmV

+3.5dBmV


Activating the Modern Return PlantInboard Test Points

LH

Coaxial

Cable

in out

3SR

Forward Test Point

LH

Coaxial

Cable

Two-way Amplifier with Test Point Inboard of Diplex Filter


Activating the Modern Return PlantOutboard Test Points

LH

Coaxial

Cable

in out

3SR

Forward Test Point

NS-6LH

Coaxial

Cable

Two-way Amplifier with Test Point Outboard of Diplex Filter

• Wavetek Model 3ST Operating Guide Section 5.1.3



• Understand your Return Path application

• Know the design specifications

• Install and configure the sweep system headend equipment

• Align the Reverse Fiber Links for uniform receiver output

• Align the coaxial plant to have least impact on transmitted signals

• Understand your Return Path application

• Know the design specifications

• Install and configure the sweep system headend equipment

• Align the Reverse Fiber Links for uniform receiver output

• Align the coaxial plant to have least impact on transmitted signals

activating the modern return plant presented by michael e. mccracken eastern show ‘96 presented by...

Documents